On the basis of previous known processor (cf. Belgian patent No. 772723), bacampicillin hydrochloride can be synthesized by the two following methods:
(A) Reaction of potassium benzylpenicillin with .alpha.-chlorodiethylcarbonate in organic solvents or in an aqueous solution of 70% dioxane in the presence of sodium bicarbonate. The 1-ethoxycarbonyloxyethyl ester of benzylpenicillin which is obtained is subjected to the reaction of removing the phenylacetic chain, via the iminochlorideimino-ether, in order to obtain the 1-ethoxycarbonyloxyethyl ester of the 6-aminopenicillanic acid, which is isolated as the hydrochloride.
By subsequent condensation of the latter intermediate with D-(-)-.alpha.-phenylglycine, the compound according to formula I is obtained.
(B) Esterification reaction of the 6-(D-(-)-.alpha.-azido-.alpha.-phenylacetamido)penicillanic acid with .alpha.-chlorodiethylcarbonate in a polar solvent.
Subsequently, by catalytic hydrogenation of the 1-ethoxycarbonyloxyethyl ester of the 6-(D-(-)-.alpha.-azido-.alpha.-phenylacetamido)penicillanic acid the compound according to formula I is obtained.
As one can see, these methods are rather complex since they involve the use of numerous raw materials and lengthy processing times.